Actually photos add credibility but not just that it also adds power to the user, the more pleasing your image to the eye is the better a user will like you. It would seem that this is just a way of Google in leveling the playing field. Akin to the idea that video killed the radio star, this approach is more of a psychological one, along with the amount of followers which could be misconstrued as the bigger it is the better you but we all know that likes can be bought anywhere. This is still somewhat sad though, I'm already used with the authorship images. :(